The present invention relates generally to the field of integrated circuits and more particularly to a parasitically compensated resistor for integrated circuits.
The gain of a transimpedance amplifier is related to the resistance of a feedback resistor. As a result, to obtain large gains it is necessary to have a large feedback resistor. In an integrated circuit, a large resistor has a large parasitic capacitance that significantly reduces the bandwidth of the amplifier circuit. One solution has been to use a transistor as the feedback resistor. This reduces the parasitic capacitance and large effective resistance values can be obtained. Unfortunately, transistors do not produce a constant resistance value for various currents. This results in an amplifier circuit that does not have a constant gain.
Thus there exists a need for a feedback resistor circuit that does not degrade the bandwidth of the amplifier circuit and provides a constant gain.